Oxygen has many important medical uses including, for example, assisting patients that have congestive heart failure or other diseases. Supplemental oxygen allows patients to receive more oxygen than is present in the ambient atmosphere. An oxygen concentrator separates nitrogen from atmospheric air to provide a highly concentrated source of oxygen. Some existing oxygen concentrators have two cylindrical containers filled with zeolite materials that selectively adsorb the nitrogen in the air. A compressor is used to force air through one of the cylindrical containers at a pressure at which the nitrogen molecules are captured by the zeolite. While air is forced through the first cylindrical container, the contents of the other cylindrical container are vented away to dissipate the captured nitrogen.
Several existing product gas or oxygen concentrators, for example, are disclosed in U.S. Pat. Nos. 4,449,990, 5,906,672, 5,917,135, and 5,988,165 which are commonly assigned to Invacare Corporation of Elyria, Ohio and fully incorporated herein by reference.